Grid problem with different size of buildings

Hello everyone,I'm making a city building game and I'm stuck on with a grid problem.

I have basic grid working but my problem is that it doesn't work good with different sizes.

Code (csharp):

1.  
2. using UnityEngine;
3. using System.Collections;
4.  
5. public class Builder : MonoBehaviour {
6.  
7.     public GameObject buildObject;
8.  
9.     public int gridSize;
10.  
11.     public Vector3 position;
12.  
13.     private GameObject ghostBuilding;
14.  
15.     // Use this for initialization
16.     void OnEnable() {
17.         ghostBuilding = Instantiate(buildObject, position, Quaternion.identity) as GameObject;
18.     }
19.    
20.     // Update is called once per frame
21.     void Update () {
22.  
23.         Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
24.         RaycastHit hit;
25.  
26.         if(Physics.Raycast(ray, out hit)) {
27.             Debug.DrawLine(transform.position, hit.point);
28.  
29.             float posX = Mathf.Round(hit.point.x / gridSize) * gridSize;
30.             float posZ = Mathf.Round(hit.point.z / gridSize) * gridSize;
31.  
32.             position = new Vector3(posX, 0, posZ);
33.  
34.             Debug.DrawLine(transform.position, new Vector3(posX, 0, posZ), Color.red);
35.  
36.             ghostBuilding.transform.position = position;
37.  
38.             if(Input.GetMouseButtonUp(0)) {
39.                 Instantiate(buildObject, position, Quaternion.identity);
40.                 this.enabled = false;
41.                 Destroy(ghostBuilding);
42.             }
43.         }
44.     }
45. }
46.  
47.  

Grid works great when building is same size as grid size(1x1),but when I put 2x2 building it doesn't follow the grid(It works on 3x3 so I guess it only doesn't work on even numbers).






This problem is bugging me for a few days ,I have tried everything but I cannot fix this.

Any help is appreciated.

 

Put your origin at a corner, not the middle of the building. Or change the points depending on building width

 

Now I feel stupid,I tried moving everything,but it was that simple Thanks for your help